The conventional portable telephone usually comprises a display panel in the upper portion of the main body, and many dialing buttons and various function operation buttons in the middle and lower portion thereof. Those buttons are provided independently, and each of dialing buttons and function operation buttons has an exclusive and multiple marking of numerals, letters and signs so that the text information may be input by those buttons. For example, the dialing buttons respectively indicate any dial number among “1-9 ” and “0” and symbols “#” and “*,” together with any letter such as Japanese Katakana Letters “(a),” “(ka),” “(sa),” “(ta),” “(na),” etc., and Latin Alphabets “A,” “B,” “C,” etc. Further, the function operation buttons respectively indicate the word(s) such as “Clear,” “Call,” “Memory,” etc., together with the symbol such as “×,” “÷,” “@,” the “symbol of telephone,” etc.
There has been provided a portable telephone as disclosed in the Official Gazette of the Unexamined Japanese Utility Model Publication No. Hei 4-103755, comprising a single and large operation disk on which the dial numbers “1-9” and “0,” and symbols “#” and “*” are marked. The rear surface of the disk has a plurality of switch mechanisms corresponding to the respective numbers or symbols on the front side. Consequently, when any portion of the disk indicating the desired dial number is depressed, only the switch mechanism under such number is turned ON. It will be the most characteristic aspect of this switch that the numbers “1-9” and “0,” and symbols “#” and “*” are collectively marked on the single operation disk.
However, according to the conventional portable telephone as above discussed comprising many dialing buttons and function operation buttons, because of the small size of respective buttons, and because of the narrow space between the buttons adjacent to each other, the operation is thereof is not easy, and there may occur an inaccurate operation. Further, since the size of each operation button is small, the acceptable size of numerals, letters and symbols marked thereon must be reduced, hence the visibility and recognizability of these markings would become poor. In particular, when used at night or in the dark place, or when used by e.g. the old people whose sight are not good, there may arise the problem that the numerals, letters or symbols will not be marked effectively.
Further, according to the “switch” disk disclosed in the Official Gazette of the Unexamined Japanese Utility Model Publication No. Hei 4-103755, it may have an advantageous point that, since the single operation disk collectively indicates the dial numbers “1-9” and “0,” and symbols “#” and “*,” it seems to become easier to depress the dial numbers. However, according to this “switch” disk, the space between each dial numbers shall become narrower, and if the depressed position is slightly out of the correct position, it will result in an inaccurate operation. Further, even in the case of “switch” disk, the acceptable size of numerals, letters and symbols marked thereon must be reduced, hence the visibility and recognizability of thereof would become still poor. In particular, when used at night or in the dark place, or when used by e.g. the old people whose sight are not good, there may be the risk of an inaccurate operation. In addition, due to the complicated structure of “switch” disk, the production cost would become higher.
In the light of technical backgrounds and problems according to the independent many operation buttons or to the switch operated by the single disk used for the portable telephones as above discussed, it is an object of the present invention to provide an operation panel of portable telephone which improves the visibility and recognizability of the numerals, etc., and secures the accurate dialing of numbers.